Barbara J. King

One can never walk the same national-park trail twice.

I’ve adapted this line from Heraclitus, who, around 500 B.C., uttered the to-be-famous “You cannot step into the same river twice.” That sentiment is even more elegant when applied to walking the diverse and wondrous trails of the American national park system.

Despite my all-U.S. theme (it’s the weekend of July 4th after all), the point stands for any nation’s preserved parks. It works especially well for parks with abundant wildlife: the Everglades in Florida and Yellowstone in Wyoming, infinitely intriguing, or Denali in Alaska and the Channel lslands off California , places I intend to visit someday.

From the Everglades, we’re back less than a week now. One highlight of my trip with my husband was a two-hour boat tour via back-country waterways – 15 sweaty tourists and a cache of deerflies riding up Buttonwood Canal, through Whitewater Bay, back down through Tarpin Creek. The mangrove ecosystem, featuring the stunning white aerial roots that eventually descend and create new trees, opened up a new eco-world to my eyes.

Fauna-girl that I am, my head (and my camera) at present teem with images of alligators and anhingas. Anhingas are beautiful birds who hunt for prey underwater and stab the unlucky victims with their beak, and we saw them on a morning’s ramble through the Anhinga Trail near the Homestead-area entrance to the Park.

We lucked out with an articulate, enthused, and funny park ranger. (His first name is Frankie, his last name regrettably lost to white-out heat-and-humidity conditions in my brain.) Out we walked, fortunate enough within the hour to see from the trail baby alligators swimming, a large soft-shelled turtle digging to lay her eggs, and birds of diverse kinds, including the anhinga.

The next day, the two of us returned to the trail, and walked it sans ranger. Baby alligators swam just in place, but no turtle. And this time, oh luck, waiting like a reward at one turn on the trail—elusive the day before and even now nearly invisible under a bush at water’s edge—was an adult alligator. In a different season we’d perhaps have encountered scores, but this single one pleased me no end. My first wild alligator!

Walking back, we came upon a gorgeous white egret in mid-hunt. His (I’m guessing at bird-gender here) body language was fantastic: stick legs mucked in shallow water, body stilled. And then it got better: he adopted an impossibly taut state, with muscles in body, head, and limbs so tight, I knew prey was near. Flash! Beak plunged into water, food caught and swallowed.

The stillness-tautness sequence was soon repeated—but this time, no luck. Egrets can’t stand in the same river twice either, it seems.

After the Everglades trip, and last year’s trip to Yellowstone, I’ve settled to the belief that every U.S. school child should spend two days in a wildlife-stuffed national park. Wildly impractical, I know, in budget-strapped 2010. (And yes, I am compelled to note that I do prioritize the jobs of superb teachers even over my beloved park idea.)

But just think of what the kids (or some of them, anyway) would learn by walking the same trail twice, or three times, or four: Life is dynamic! Starting from hour-to-hour, day-to-day trail observations, the lesson could swell out: Animals adapt to changing conditions, whether those within a day or a season or a much longer evolutionary time period.

Do you have a favorite national-park trail, one that can’t be walked the same way twice?